Many businesses use a Virtual Private Network (VPN), or multiple interconnected VPNs for handling larger amounts of information, to support confidential communication. VPNs use tunnel protocol paths, or in a specific configuration, Label Switched Paths (LSPs), allow information (commonly called traffic) to travel between two network elements (e.g., routers) by providing a path on which traffic can travel. VPNs can vary in degree of complexity depending on the number of devices between two Customer devices. For example, the two Customer devices could be a laptop computer communicating with a server.
When multiple VPNs are interconnected, core LSPs often carry traffic for more than one VPN similar to non-core LSPs that carry traffic between two routers. A set of core LSPs make up an overall data plane. Many MPLS VPNs use Virtual Routing and Forwarding (VRF) to allow multiple data planes to co-exist in the same router at the same time. In these configurations, VPN message traffic travels either over the Internet or over a service provider's private network. A Service Level Agreement (SLA) is used to define an area of a private network used by a VPN user. An SLA is generally a part of a full service contract between a VPN service provider and a VPN customer.
The use of VPNs has become prevalent in recent years. There are numerous benefits to using VPNs. One benefit is that VPNs allow for secure communications in areas where there is limited communication security. A further benefit arises because a single location can manage numerous remote locations, allowing for greater network support. Moreover, VPNs allow secure communication across vast distances. For example, a device in India can securely communicate with a device in Great Britain. There are also secondary benefits that follow from secure, long distance communication. For example, integrated communication between two individuals in different countries can greatly reduce mailing costs, travel costs, and other costs incidental to conventional forms of communication.